1. Field of the Invention
The invention relates to a backlight module, and more particularly, to a backlight module having a thermal insulation light guide element.
2. Description of Related Art
In a conventional side type backlight module, a light emitting diode (LED) is required to be placed closely to a light guide plate, such that light beam emitted by the LED may be effectively guided into the light guide plate. However, about 70% heat is produced when the LED is turned on, such that temperature at an edge of the light guide plate near the LED rises above a glass transition temperature of the light guide plate due to the heat. As a result, the light guide plate is warped because of the increasing temperature difference between the temperature at the central region and the temperature at the edge of the light guide plate. And as the size of the backlight module becomes larger and the light guide plate gets thinner, the wrap due to unevenly heating becomes more and more obvious. On the other hand, as limited by white light packaging technique, non-uniformity of brightness and color in the backlight module occurs when a white LED and a square lamp cover are employed together. Besides, the conventional square lamp cover may not control the light emission distribution of an LED.
Furthermore, U.S. Patent Application Publication No. 20080291694 discloses a backlight module including a point light source, a first light guide plate, and a second light guide plate. The second light guide plate takes the shape of a plane and is disposed between the point light source and the first light guide plate. A material of the second light guide plate is polycarbonate (PC). Moreover, US Patent Application Publication No. 20080225203 also discloses a backlight module including an LED light source, an optical reflecting material, and a light guide plate. The optical reflecting material is disposed on an upper portion of a space between the LED light source and the light guide plate, such that light leakage through the upper portion of the space is prevented.